The clock at Buchenwald was stuck at 3:15. The White House advance guy noticed, and put it on the list of things to fix.
The 23-year-old laughed at himself when he learned the clock's hands were deliberately frozen, marking the exact time the concentration camp was liberated in 1945.
During the week Josh Lipsky spent getting Buchenwald ready for his boss' visit to the camp Friday, the clock would come to mark something other than schedule, precision, his own readiness.
He would live a little in that moment trapped in time alongside the grandfather he never knew -- and would know himself better when he left.
Lipsky grew up knowing that his grandfather and grandmother had met and fallen in love somewhere in the network of Nazi camps near the Polish border. He also knew that they were separated when his grandfather was sent to Buchenwald.
"I knew they had met in the camps," he said, "but I didn't know the circumstances."
When word spread around the White House that Obama would go to Buchenwald, Lipsky asked to go. Though he now works in the visitors' office, helping to arrange official functions, he spent the campaign on the exacting task of advance work and still sometimes volunteers for big projects.
It seemed only right to visit Buchenwald, where more than 50,000 people were killed during the Nazi regime, and to finally delve into the family story. Lipsky -- who graduated from Columbia University last year, then went out on the campaign trail -- figured he'd just prepare like he prepares for any advance project.
On the flight to Germany, he listened for the first time to the oral history that his grandmother, Helena Langer, had recorded for a Holocaust foundation before she died. He'd been nervous about hearing it, but now that he was going to the camp, he knew he had to listen.
In it, she tells her story, of a young woman who fell in love with the camp cook, the man she would later marry.
The cook, Samuel Smulowitz, was 26 when the Nazis took him from his home outside Krakow, Poland, and sent him to a camp near the border with Germany.
The young Helena was in another labor camp nearby. She was singing a song on the way to her barracks one day, and some SS guards were so angered by the sound that they attacked her with a German shepherd and beat her mercilessly.
Too badly injured to work, she was on her way to Auschwitz -- and probably her death -- when her train broke down. She ended up in the infirmary of Samuel's camp.
Being a cook was a good thing in the hierarchy of the camp, his grandmother's story goes on. He could move around the camp. He could bring food to the sick. He had access to the infirmary register, and a pen.
"He substituted the name of a dying woman with her name," Lipsky said. The older woman went to Auschwitz in his grandmother's place.
The two were parted when the cook was sent from the camp to Buchenwald, and they nearly lost each other.
After liberation in April 1945, Helena followed rumors about Samuel to several German and Polish cities, jumping from trolley to trolley with his picture.
At the back of a car in Munich, she finally found her cook. "I'm here. You don't need to look any further," he said, according to a family transcript of the grandmother's tape.
They married, immigrated to the United States, opened a kosher butcher shop in Louisville, Ky., and raised three children. One of them is Miriam Gabriela Lipsky, Josh's mother.
What had been lost in the story, though, were the details of Samuel Smulowitz's time at Buchenwald. He died in 1975, 30 years after the clock at Buchenwald stopped moving but a decade before his grandson was born.
By the time Lipsky got to the camp last week, its caretakers already knew of his connection from other young staffers already there. Within hours of his arrival, the information began to flow.
A guide found a letter from a prisoner, telling of a camp cook in the later years of Buchenwald who used to line his clothing with potatoes and sneak them to the hungriest. The detail about hiding food in the lining mirrored a fragment of information from his grandmother's tapes.
Later, someone from the camp's foundation came to him with his grandfather's check-in slip, on which the young cook had signed his name -- in a manner bearing a striking resemblance to the way Lipsky writes his own signature. Each extends the leg of the last letter to underline the rest of his name.
As he moved about the grounds, Lipsky passed sights that he knew his grandfather had seen -- the nearby woods, the barbed wire, the zoo just outside the fence where Buchenwald guards brought their children to see the animals in one set of cages and the humans in another.
But it wasn't until the end of the week that he stood in a long-hidden room in what was certainly his grandfather's domain, the cellar below where the kitchen once stood.
"The guide who took me down there had never been there," Lipsky said. Very few had, the longtime employee said.
The door's hinges were rusted over. They had to take them off with a wrench.
The guides illuminated the cellar with mine shaft lights, and Lipsky saw walls with peeling paint. Rusted wagons sat among the crude pantries.
Lipsky saw a rusted old chute coming down from the kitchen, and moved beneath it.
"He would have stood there under the potato chute," he said. "Some SS guard, or maybe another prisoner, would have thrown down a bag of potatoes and he would have had to catch it.
"That's the moment when I knew I was standing in my grandfather's place."
He said Kaddish, a Jewish mourning prayer.
When he went back to preparing for the president's visit, he felt that his grandfather was with him.
He did the final walk-through of the path the president would follow.
On the morning of the visit, he greeted the busload of reporters and moved them to their positions near the gates of the camp.
When Obama took his place -- beneath the clock proclaiming the time to be 3:15 -- Lipsky knew the exact number of paces between Obama and the bank of cameras, where he also stood. He listened there, 21 steps from the president. He did not check his watch as the president spoke of a song written by Buchenwald prisoners with lyrics that pledge, "We will say yes to life."
"These individuals never could have known the world would one day speak of this place," Obama said. "They could not have known that some of them would live to have children and grandchildren who would grow up hearing their stories and would return here so many years later to find a museum and memorials and the clock tower set permanently to 3:15, the moment of liberation.
"They could not have known how the nation of Israel would rise out of the destruction of the Holocaust and the strong, enduring bonds between that great nation and my own.
"And they could not have known that one day an American president would visit this place and speak of them and that he would do so standing side by side with the German chancellor in a Germany that is now a vibrant democracy and a valued American ally.
"They could not have known these things," he said. "But still, surrounded by death, they willed themselves to hold fast to life."
After the speech, friends saw Obama pull Lipsky into a hug. Asked about it, Lipsky said he didn't want to disclose the details of the private moment.
He packed his bags and flew back to Washington on Saturday. He wanted to see his mother in suburban Maryland right away. He wanted to fill in the gaps of the story for her. He wanted her to know what it meant to him.
"He worked in the kitchen," he said before he left Germany for home. "I am his grandson. And I came here working for the president of the United States, and that's a powerful thing for me."